Electron discharge device



ept 6, 19. P. L. SPENCER A U ELECTRON DI S CHARGE DEVICE Filed Aug.. 20,1945 Y 2 Sheets-Sheet l S 1. E, 1919. P. SPENCER ELECTRON DISCHARGEDEVICE 2 Sheets-Sheet 2 Filed Aug. 20, 1945 Avm'Mm/fi. We y A 5FEA/6W?(24% J l L 3 x/ M Hal Il H &1.- 3 1 MW A patented Sept. 6, 1949 UNITEDSTATES ELECTRON mscHARe-n Device P rcy Snencer We ewton Mass a si n?! Be M aewrf g Qemneem New .ton,.Ma ss., a, corporation .ofipelawareApplication August 20, IMEQSeriaL-No. $1 1,459

My present invention relates to .electronegiss charge devices, and moreparticularly to tunable electron-discharge devices.

while notllimited thereto, my present invention is especially suitablefor tuning eleotronedischarge devices of the so-called magnetron type.

Themain object of my present invention is to nrovidezmeans for tuning aneleetronadischarge device through .a :much greater frequency range ithanhas heretoforeie'een possible, and 13011113 end 'iIsoconstruct the.devieethat both-the canacitance andjnductanee thereof aresimultaneously varied, reach .to a considerable degree, and in the same:direction.

This, and .otherxibiects rofzmy presentinuentien, which will become moreapparent as the detailed description thereof aprogresses, are attained,hriefly, in the following manner:

As above stated, :my present inventienl-is par.- iticularl-ywe'lladapted .to the tuningicf electron- -discharge devices iof the magnetrontape. :ljprefer that said device include at "least one electrode, forexample, the anode thereof, :in therfor-maof a cylindrical structure,made cfihighly conductive material, such as copper, and .provided with"a iluraflityuf interiorl-yextended,rradially-dispnsed anode members,each adjacent :pair otsaid anode members, together with that portion ofsaid anode structure lying therebetween,- constituting "malls defining:a cavity resonator.

:I provide :at least some of said defining swells, preferably, thesecomprised of said anode :members, with at least one gap therem,saidgaptseryiing 1130 :increase the distrihuted inductance of :each

anode member provided therewith rover .what :it 1

control .over the inductance, generally, of the device. As a "mattercf.iact, either oi ithle abovedescribed inductance-.controlling expedientsmay zbe zutilized alone, although, stated, vit is preiierred that theybe .used together.

I further provide said anode .members'with at lea-st one paircfconducting straps whicheltermately contact successive anode members, thestraps ef each pair-being so disposed with-respect to eachother-so:astopresentacapacitanceithere- C a ms. (01.259 121-5) AS63119? W131 .imistrazw embeeinem elee i :2 into the space bet a pm iliere ir 9i ai wndnti-ne straps, .1 able to alte h inte strap. capac tance, sa d mieretreeeeepiieeee h me minimum said c nductin membe is entire y with rawnir mhei sen said serenel hus, names ins b th of t were re ereed Q conductingmembers with respect to said gaps and .eavit re enamr-erases. eee eis res lam-a m alter thesis-br e. .e i mew-tense as the ist bute sapecit ee wth re he d v e a e mmtione ih eeemetrr-mereet an; s} ime sa d devic t afre uenc -othe teen 1, .5 ea e l e ane i equsnpy- :eneierael t il; ofsaw ener t n mem r a e movable smi Q sa d eed m me bers be n withdrawn hs n cavit 'lQ$9 -Q P%Z e the 9 h?! een lmfie member is ini qc u esretirees-the st aps th r b alter n :beth t e i siaetaeee a cap n at thesame time, in thersarne action, and enablin the att inmen o p iab aueneyd i iatiee, whi h s semiei we an substantiall lin ar- -.I t at marr isneqifiqei 1. hel dein the lei-b esses t ewin s Sho devices f 2 67EPIIESBKIP i ilil i r i1 hq v' r to he lea ly nnrie siee t a 5! 9 m Wi ht9 be lim t dt the de s -he in sh wn summar se e mnpqs s e e iys re ieneels, zchanees t erei new e mad? wi h nt iht e e ef inrentme nd t t ue pi an s en Q the main est e eeee dsfi- "in-said d aw n J .1 is e lneitufliee e ptie ie ne aken substantially through the center of atunable meene ron sense in eesesa anee w th t e te t m s! my n sen inveml F -2 seitee sees e w we 3 11 tion of said magnetrqz 1 ,.;mpre learlyshowing the eleiiqneh n ib iweee he oa seness 9 the abo e erred t tuninmeals- Herarrme {n w more n de ai to t e a o esa i lustrative em qriimet o my e n ieven ee an w th e rtieula eterenc o th dr w n s-i ttatmsthe same t e ru ?era 1 e i e vdes nates an electroneri s ha ie ti e @QWe $.0- caile imaen t onetxn fiai de e c mnniaes a an d t tu tu ie :5. acei ede :SFEUPWYB 1, ma netic :means :8 for establishing a magneticzfield in a direction rpemendmular to the path of the electron-flow:between said ,:cathode and anode structur and tuning 1111321 1823- in:the device shown, the =ano de structure 6 1nhetween. By introducing aconducting member :clncles 'aicylindiealzboay All fgmadefifhiehlrconductive material, such as copper, said body being provided witha multiplicity of radially-disposed, interiorly-extending anode membersin the form of vanes ll, each adjacent pair of said vanes, together withthat portion of said cylindrical body lying therebetween, defining thewalls of a cavity resonator whose natural resonant frequency is, as iswell known in the art to which my present invention relates, a functionof the geometry of the physical elements making up the same. I shallfurther describe the anode members when reierrlng, in a later portion ofthis specification, to the details of the tuning means 9.

The anode structure is closed at its ends, for example, by end plates l2and I3, with the junctions between the cylindrical body Ill of saidstructure, and said plates l2 and I3, hermetically, sealed, as at M.

'lhe cathode structure 1, which is coaxial with the anode structure 6,includes a cathode sleeve I5, conventionally made of nickel, or thelike, provided with a reduced portion l6 whose length, preferably, iscoextensive with the width of the anode members said reduced portion I6being provided with a highly electron-emissive coating H, for example,or the well-known alkaline-earth metal oxide type.

In oruer properly to support the cathode sleeve In with respect to theanode members said sleeve may be reduced, as at I8, to fit into anelongated, electrically-conductive tubular memher Is having, at itsouter end, a ferrule 20 closed by a glass seal 2|. Said seal, togetherwith one or more glass beads 22 disposed within the tubular niemoer is,support a lead-in conductor 23 which passes through said member l9 andhas its upper end connected, as at 24, to one terminal of a cathodeheating filament 25. The other terminal or said filament may beconnected, as at 25, to the cathode sleeve l5.

In order to convey current .to the filament 25, the lead-in conductor 23is connected by a conductor Zl to one terminal of a suitable source ofvoltage (not shown), the other terminal of said source of voltage beingconnected by a conductor 28 to a heat-dissipating member 29 fixed uponthe lower end of the tubular member |9.

In order properly to support the cathode 1, and insulate the same fromthe anode structure 5, the tubular member I9 may have fixed thereto acup-like bushing 3i] sealed into one end of a glass tube 3|, the otherend of said glass tube having sealed therein a tubular bushing 32, inturn, secured to a tubular pole piece 33, constituting one of thecomponents of the magnetic means 8.

Said pole piece 33 may be hermetically sealed. as at 34, into the endplate l3, and be provided with a central bore 35 whereby the cathodestructure 1 may enter the device.

Another tubular pole piece 36 may be hermetically sealed, as at 31, intothe end plate l2, said pole piece and the pole piece 33 being fixed, forexample, to the opposite ends of a horseshoe magnet 38 (only partiallyshown), whereby an, appropriate magnetic field may be established, aspreviously indicated, in a direction perpendicular to the path of theelectron-flow between the cathode structure 1 and anode structure 6.

' Now, by suitably heating the cathode, and applying a proper potentialdifierence between said cathode and the anode, the device can be made togenerate electrical oscillations of a wave length determined, primarily,by the capacitance and inductance built into said device as a functionof the geometry thereof, and more especially, of the dimensions of theabove referred to cavity resonators defined by the anode structure.

In order to extract power from the device I may, for example, introducea loop 39 into one of said cavity resonators, said loop coupling withthe magnetic component of the above-mentioned electrical oscillations.Said loop may, in turn, be connected to a conductor 49 supported in aglass seal 4| fused into an outlet pipe 42, said pipe being threaded andhermetically sealed into the cylindrical body ll) of the anode structure5.

In the device thus far described, there is no external control over thefrequency of the gem erated oscillations, and in order to overcome thisdeficiency, I proceed as follows:

Each anode member [I is provided, preferably, in both its upper andlower edges, adjacent its inner end, with cutaway portions or slots 43,each slot being defined by a straight bottom edge 44, a straight sideedge 45, and a shouldered side edge 46, the shoulder being designated bythe reference character 41. Said upper and lower slots are laterallyreversed with respect to each other, whereby the straight side edge 45of one of said slots, say, the upper slot in the particular anode memberI being described, is in substantial alignment with the shouldered sideedge 46 of the lower slot in said anode member, and the shouldered sideedge 46 of said upper slot is in substantial alignment with the straightside edge 45 of said lower slot. By so forming each anode member H, andinverting adjacent members with respect to each other, a single type ofelement can be utilized for all of said anode members.

I now provide an annular member or strap 48, which seats upon all of theshoulders 41 of the side edges 46 of the upper slots 43 in alternateanode members said strap clearing the straight side edges 45 in theadjacent, inverted anode members. I also provide a similar, butsmaller-diameter strap 49, which seats upon the shoulders 41 of the sideedges 46 of the upper slots in said adjacent, inverted anode members,

said strap 49 clearing the straight side edges 45 in saidfirst-mentioned alternate anode members.

The straps 48 and 49 are thus concentrically disposed with respect toeach other, and present a capacitance therebetween which enters into thedetermination of the natural resonant frequency of the device.

The lower slots 43 in :the anode members may, if desired, also beprovided with concentrically disposed straps 50 and 5|, and if suchstraps are provided, they, too, enter into the determination of thenatural resonant frequency of the device.

It has been found that when alternate anode members are electricallyinter-connected as just described by the straps 48 to 5| inclusive,spurious oscillations become suppressed.

Now, it has also been found that inasmuch as the straps of each pairthereof have a capacitance therebetween, and they may be considered theplates of a capacitor, by varying said capacitance, and introducingadditional capacitance in parallel therewith, the device can be tuned,and to this end, I proceed as follows:

A plunger 52, made of highly conductive material, such as copper, isslidably mounted in the bore of the tubular pole piece 36, the inner endof said plunger being recessed, as at 53, to accommodate the upper endof the cathode structure 8, and the extremity thereof-being cupped toprovide a conducting annulus 54, which, when moved, for example,intermediate the straps It and 49, constitutes, together with saidstraps, a variable capacitor. In order to maintain the device air-tight,I provide an apertured flexible diaphragm 55, hermetically sealed, atits periph-i cry, to the cylindrical body to of the anode struc: ture 6,and similarly sealed, at its central apers ture, to said plunger ti.

The introduction of the annulus -54 into. the space between the straps48 and 4% does two things. First, it reduces the effective area of thesurfaces of said straps between which the aboves mentioned capacitanceexists, but inasmuch as this capacitance is small to begin with, theovers all effect on the frequency of the'device is, like wise, small.Second, it forms, together with said straps, two capacitors, connectedin series, which did not, before, exist. Inasmuch as the gaps betweensaid annulus and said straps are small, the total capacitance of thenewly formed capacitors is relatively large, and this capacitance, addedin parallel with what remains of the original capacitance, has aconsiderable effectupon the frequency of the device.

I shall now describe my means forvarying the inductance of the device.

I provide at least some, and preferably, all oi the anode members orvanes It, at the'lower, outer cornerthereof, with gaps 56. A conductingring 51 is adapted to. be moved in and out of said gaps 55, therebyaltering the distributed inductance of each vane it provided with such agap. Now, the ring 51 being, preferably, continuous, its movement withrespect to the gaps 58 results in its movement in and out of the spaceof each cavity resonator. This provides additional control over theinductance of the device. The ring 5! may be secured at the lower end ofa cylindrical shell 58 nested within, but spaced from, the cylindricalbody W, said shell being provided with slots 51% and 59 to accommodate,respectively, the vanes H. and the loop- 39. The upper end of the shellas may be provided with a horizontal disc 50, with which the annulus 54may, if desired, be integrally formed.

There remains to be described the control mechanism of the tuning means9, by means or which there may be brought about the hereinbeicredescribed relative movement between the annulus 54 and straps to and 48-and the ring 51 and gaps 56.

While not limited thereto, I prerer-to construct such tuningcontrolmeansas follows:

Secured on t u per and o t pl n er 52 is a threaded bushing Blengageable in a disc 62 whose periphery may be, provided with a V-cut63, constituting a ball-bearing race.v Qu-rroundy me sa d race isanother. ace compr se of two cooperating bevelled rings 64* and 65', thering 64 being carried by a disc 65, and the ring 6-5 being pres d ntoperation. wi h g (it by" an annular spring 6 l The races are; receptivetheretwcen of bear n balls. 6 and the spring: '6?! is xec the 6. by a.at... reta ni ri 89 and bolts it.

The disc 66 is maintained against rotation by being bolted, as at H, toa plate 12 fixed, at its center, to the pole piece 36, the plate 12being provided with bearings 13 in which is journalled a shaft M.Mounted upon the shaft 14 is a worm gear l5 engageable with a worm wheel16 secured to the disc 52 by means of bolts 11. The shaft 14 isprovided, at one end, with a pinion (not shown), oranyother meanswhereby the same may be manually or otherwise rotated, slidably to. movethe. plunger- 52. with respect to the pole piece 38, andthus vary thecapacitances between the straps 4.8 and 49, the inductances of the vanesl i provided with the gaps 56., and the inductance, generally, of eachcavity resonator.

In order to protect. the device against damage which might be caused byexcessive movement of the plunger 52, I provide means for limiting therotation ofthe worm wheel 1%.. Such means may comprise a cam la.pivotally mounted upon a bolt 19 which is fixed in a bracket 86 carriedby the plate l2, said cam having a tooth Bl co operable with a pin 82carried by the worm wheel 16. The arrangement is such that. the firsttime the pin 82 approaches. the cam '18, it. engages the tooth 8.!thereof and trips the same, whereby the next time the pin 82 comesaround, it abuts the surface of the cam-and cannot pass the same.Rotation of the worm wheel in the opposite direcion causes. a reverseddisposition of the cam, thereby limitin Saidrotation to two. revolutionsin each direction,

'lf is completes the description of the aforesaid illustrativeembodiment of my present invention, It will be noted from all of theforegoing that I a e provided relatively simple means for tuning n c o-discharge device. particularly, a magnetron, through an appreciablefrequency an e. e nin means of my present. invention enabling multaneousalteration, in the same direction, of both the. inductance andcapacitance of? the device. It. will also, be noted that the fies quencydeviationfthereby obtained is continuous and linear.

Qther objects. and advantages of my present inv n i n Willrcadily occurto those skilled in the ar t which, he. same relates.

What-is claimed is:

1. A tunable electron-discharge device comprising: an electrode.structure provided with electrode members; each pair of adjacent eletrode members, together with that portion ofsaid electrode structurelying therebetween, con stituting walls defining a cavity resonator; thedefining walls of atleast. one ofsaid cavity resonators being providedwith a gap therein form-. ing part: of the distributed inductancethereof; spaced means. cooperable with the defining walls ofat least oneof said cavity resonators, prcsenting, in parallel with the distributedcapacitance thereof, an additional distributed capacitance; and means,carried by said device and movable into and out of each of said gaps andintermediate. said spaced means, for simultaneously altering, inthe samedirection, said distributed indnctance and said lasthamed distributedcapacitance.

2. A tunable electron-discharge device com-- prising: a cathodestructure; a cylindrical anode structure surrounding said cathodestructure, and provided with a plurality of inwardly-di rected',radially-disposed anode members; each pair of adjacent anode members,together with that portion of said anode structure lying there'-between, constituting walls defining a cavity resonator; the definingwalls of one of said cavity resonators being provided with a gap thereinforming part of the distributed inductance thereof; means, cooperablewith the defining walls of said one of said cavity resonators,presenting, in parallel with the distributed capacitance thereof, anadditional distributed capacitance; a shell, movably mounted in saiddevice,

and having slots in one of .the walls thereof for straddling said anodemembers; and means, carried by said shell and movable thereby withrespect to each of said gaps and said last-named means, forsimultaneously altering, in the same direction, said distributedinductance and said last-named distributed capacitance.

3. A tunable electron-discharge device comprising: an electrodestructure provided with electrode members; each pair of adjacentelectrode members, together with that portion of said electrodestructure lying therebetween, constituting walls defining a cavityresonator; the defining walls of at least one of said cavity resonatorsbeing provided with a gap therein forming part of the distributedinductance thereof; a pair of conductors alternately contacting saidelectrode members; said conductors presenting a distributed capacitancetherebetween; and means, carried by said device and movable into and outof each of said gaps and intermediate said conductors, forsimultaneously altering, in the same direction, said distributedinductance and said inter-conductor distributed capacitance.

4. A tunable electron-discharge device comprising: a cathode structure;a cylindrical anode structure surrounding said cathode structure, andprovided with a plurality of inwardly-directed, radially-disposed anodemembers; each pair of adjacent anode members, together with that portionof said anode structure lying therebetween, constituting walls defininga cavity resonator; the defining walls of one of said cavity resonatorsbeing provided with a gap therein forming part of the distributedinductance thereof; a pair of conductors alternately contacting saidanode members; said conductors presenting a distributed capacitancetherebetween; a shell, movably mounted in said device and having slotsin one of the walls thereof straddling said anode members; and means,carried by said shell and movable thereby with respect to each of saidgaps and said conductors, for simultaneously altering, in the samedirection, said distributed induct-' ance and said inter-conductordistributed capacitance.

5. A tunable electron-discharge device comprising: an electrodestructure provided with electrode members; each pair of adjacentelectrode members, together with that portion of said electrodestructure lying therebetween, constituting walls defining a cavityresonator; the defining walls of one of said cavity resonators beingprovided with a gap therein forming part of the distributed inductancethereof; a pair of conductors alternately contacting said electrodemembers; said conductors presenting a distributed capacitancetherebetween; means, carried by said device and movable with respect toeach such gap, for altering said distributed inductance; a thirdconductor, movable intermediate said first-named conductors, foraltering said inter-conductor distributed capacitance; and adjustablemeans, carried by said device, for moving said last-named means and saidthird conductor as a unit, whereby the alterations in said dis- 8tributed inductance and in said distributed ca pacitance' aresimultaneous, and in the same direction.

6. A tunable electron-discharge device comprising: an electrodestructure provided with electrode members; each pair of adjacentelectrode members, together with that portion of said electrodestructure lying therebetween, constituting walls defining a cavityresonator; the defining walls of one of said cavity resonators beingprovided with a gap therein forming part of the distributed inductancethereof; spaced means, cooperable with the defining Walls of said one ofsaid cavity resonators, presenting, in parallel with the distributedcapacitance thereof, an additional distributed capacitance; a conductingring, movable into and out of each of said gaps, for altering saiddistributed inductance; means, carried by said device and movableintermediate said spaced means, for altering said last-named distributedcapacitance; and means, connecting said conducting ring and saidlast-named means, for moving said conducting ring and said lastnamedmeans as a unit, whereby the alterations in said distributed inductanceand in said lastnamed distributed capacitance are simultaneous, and inthe same direction.

'7. A tunable electron-discharge device comprising: a cathode structure;a cylindrical anode structure surrounding said cathode structure, andprovided with a plurality of inwardly-directed, radially-disposed anodemembers; each pair of adjacent anode members, together with that portionof said anode structure lying therebetween, constituting walls defininga cavity resonator; each of said anode members being provided with a gaptherein forming part of the distributed inductance thereof; a pair ofconductors alternately contacting said anode memhere; said conductorspresenting a distributed capacitance therebetween; a shell, movablymounted in said device, and having slots in one of the walls thereofstraddling said anode members; a conducting ring, carried by said shelland movable thereby with respect to each of said gaps, for altering saiddistributed inductance; a third conductor, carried by said shell andmovable thereby intermediate said first-named conductors, for alteringsaid inter-conductor distributed capacitance; and means carried by saiddevice for moving said shell, whereby the alterations in saiddistributed inductance and in said distributed capacitance aresimultaneous, and in the same direction.

- PERCY L. SPENCER.

- REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,348,986 Linder May 16, 19442,404,212 Bondley July 16, 1946 2,408,237 Spencer Sept. 24, 19462,424,496 Nelson July 22, 1947

